Can a Tomcat docBase span multiple folders?

Question

I apologize if this is a poor question, but I'm using Windows and looking to see if there's a way to run a webapp via Tomcat where the docBase is multiple folders.

A little more background is that we have our Eclipse project set up in a way that the web content is broken into separate folders. One folder represents what our SDK provides, one is a folder which has SDK patches, and a third is the project-specific components -- either of the last two folders could have subfolders/files that "erase" items from the first two.

I'd like to try and have my context file point back into my dev environment so that I don't need to build/deploy in order to see the changes I'm making. Is this possible?

A couple other notes:

• We thought about using symlinks via mklink, but didn't want to create complexity if simplicity was out there.
• This is just for running locally so simple hacks would be allowed. When we create the WAR which gets deployed to the real environment the ANT script creates a single web root.

Answer 1

I use it this way:

    <Context docBase="jquery"                path="/js/jquery" />
    <Context docBase="foobar/www/javascript" path="/js" />
    <Context docBase="foobar/www/css"        path="/css" />
    <Context docBase="foobar"                path="/" />

Important for the concrete context is the path-attribute. A request is processed from top to bottom.

So a request for /css/default.css is only processed from the 3rd context.

A different order may catches a different context.

This is wrong:

    <Context docBase="foobar"                path="/" />
    <Context docBase="jquery"                path="/js/jquery" />
    <Context docBase="foobar/www/javascript" path="/js" />
    <Context docBase="foobar/www/css"        path="/css" />

Because /css/default.css will be catched by the first context, not the fourth.

Edit 2013-08-10: (Not by the answer-author) It is important to note that while the above technique will work, much of it is actually incorrect. Please see comments for details.

Answer 2

Tomcat can do this for you, you just need a little extra configuration.

You are looking for VirtualDirContext which allows you to specify a list of extraResourcePaths which will be searched (in order) for additional files. You can use that to merge static resources, JSPs, directories of JAR files, etc.

Just remember that each path you add makes every file lookup potentially take longer -- especially if the file can't be found at all.